The Human-to-Human (H2H) communication is that persons communicate by operating devices. Current wireless communication technology is developed based on H2H technology. In a narrow sense, the definition of Machine-to-Machine (M2M) communication is communications between machines. While in a broad sense, the definition of M2M is the networked applications and services based on intelligent interactions between machine terminals. The M2M communication technology is based on intelligent machine terminals and uses multiple communication modes as access means, so as to provide users with informatization solutions to satisfy the informatization requirements of users in monitoring, command and dispatch, collection and measure of data.
The development of wireless technology is an important factor for the market development of M2M, which breaks through the time and space limit and the region barrier to liberate enterprises and public from cable constraint, so as to allow clients to control the cost more effectively, to reduce the installation charge and to use simply. Additionally, the increasing demand pushes forward the M2M to develop continuously. However, in contrast with the increasing information processing ability and network bandwidth, the measure for acquiring information falls far behind. The M2M technology satisfies this requirement very well. Through the M2M technology, people can monitor external environment, so as to realize automatic information acquisition in large area. Therefore, the industry application includes traffic monitoring, warning system, salvage, vending machine, electronic toll collection and so on, and the home application includes automatic meter reading, temperature control, and the personal application includes life detection, remote diagnostics and so on.
The object of M2M communication is machine-to-machine or human-to-machine. The data communication between machines is defined as Machine Type Communication (MTC) and in this case, human-machine interaction is slightly required. The machine participating in MTC is called as MTC device or MTC terminal, a MTC device is capable of communicating with other MTC devices or MTC servers through Public Land Mobile-communication Networks (PLMN).
After the introduction of the MTC application, some optimization can be made on the current communication system according to the characteristics of MTC to satisfy the requirements of the MTC application, without any impact on normal User Equipments (UE) in the current network. Some of the outstanding characteristics of the MTC application comprise: there are a large number of MTC devices, and the data amount for each transmission is small, large interval between transmissions and a part of MTC devices have relative fixed positions. According to statistics, the number of MTC devices installed within the scope of a community in a certain city will reach 3000, when those MTC devices initiate random access intensively, such as giving alarms when a fire or an earthquake happens, such a large number of MTC devices will produce a prodigious impact to the network. In general, multiple base stations will be connected to a same network element of the core network, such as a mobility management entity (MME). When a numerous of MTC devices in all base stations need to access to the network, for example, all MTC devices need to re-register to the network during a power recovery after an outage, the MME will bear a tremendous signaling impact and even lead to overload.
when a numerous of MTC devices intends to access to the network, a large amount of random access resources and dedicated resources will be occupied, wherein the dedicated resources include Physical Downlink Control Channel (PDCCH) resources, Physical Uplink Control Channel (PUCCH) resources, Physical Downlink Shared Channel (PDSCH) resources and the like, which can cause the occurrence of overload for random access resources and dedicated resources, and thus affecting service application of normal H2H devices. Thus, it is necessary for the base station to adjust the access control parameters dynamically based on its load conditions, and a part of terminals may be rejected or released, so as to control the load reasonably.
If a terminal has accessed the network and the service is on the fly, the base station will release radio resource control (RRC) connections of a part of terminals and radio resources to reduce the load of MME when an overload occurs at the network side. After that, if a released terminal needs to carry out a service again, it needs to rebuild an RRC connection, re-initiate a random access, re-execute an encryption procedure and re-establish a service bearer. These procedures will consume a lot of radio resources and occupy multiple air interface signalings, which will increase the processing load of the base station and the processing load of MME.